A cropmark, the faint shadow of an ancient enclosure roughly forty metres across, betrays its presence only when dry weather stresses the vegetation above it, causing crops to ripen unevenly over the buried ditches and banks below.

The site is classed as a univallate circular enclosure, meaning it was defined by a single surrounding ditch or bank rather than the multiple rings found at more elaborate sites. Enclosures of this type are common across Ireland and are generally associated with the early medieval period, though many have earlier or later origins. They served various purposes depending on their context, from ringforts used as defended farmsteads to ritual or burial sites. At Ballymorisheen, the evidence comes entirely from aerial observation of cropmarks recorded through the CASAP programme, a systematic aerial survey of Irish farmland that captured thousands of previously unrecorded sites by photographing fields during favourable growing conditions. The enclosure itself has never been excavated, so its precise date and function remain unknown.